package com.tutu.utils;

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.codec.binary.Base64;

import javax.crypto.Cipher;
import java.nio.charset.StandardCharsets;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.SecureRandom;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

@Slf4j
public class RSAUtils {

    private final static String PUB_KEY =
            "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCEC1Q/HFy7cL0PsrPqhjH2GZNIL5K8dhf0FkOKrOSjw5rTb8kC046CGwaFCioMyaS5sgBfykB0xFemTkc67BYGh6D/JkUicQGNJMc2gIbFgmaYRCy3MOc3owofQaDZtLNqZjYrynRlVg7I03i0iyBBK5NYeOk6G/vt9R9DNvFghwIDAQAB";

    private final static String PRIV_KEY =
            "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";

    public static Map<Integer, String> genKeyPair() {
        // 用于封装随机产生的公钥与私钥
        Map<Integer, String> keyMap = new HashMap<>();

        try {
            //  KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
            KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");

            // 初始化密钥对生成器，密钥大小为96-1024位
            keyPairGen.initialize(1024, new SecureRandom());

            // 生成一个密钥对，保存在keyPair中
            KeyPair keyPair = keyPairGen.generateKeyPair();
            RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); // 得到私钥
            RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); // 得到公钥

            // 得到公钥字符串
            String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));

            // 得到私钥字符串
            String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));

            // 将公钥和私钥保存到Map
            // 0表示公钥 // 1表示私钥
            keyMap.put(0, publicKeyString);
            keyMap.put(1, privateKeyString);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return keyMap;
    }

    /**
     * RSA公钥加密
     *
     * @param str 需要加密的字符串
     * @return 公钥加密后的内容
     */
    public static String encrypt(String str) {
        String outStr = null;

        try {
            // base64编码的公钥
            byte[] decoded = Base64.decodeBase64(PUB_KEY);
            RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));

            // RSA加密
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE, pubKey);
            outStr = Base64.encodeBase64String(cipher.doFinal(str.getBytes(StandardCharsets.UTF_8)));
        } catch (Exception e) {
            e.printStackTrace();
        }

        return outStr;
    }

    /**
     * RSA私钥解密
     *
     * @param str 加密字符串
     * @return 私钥解密后的内容
     */
    public static String decrypt(String str) {
        String outStr = null;

        try {
            // 64位解码加密后的字符串
            byte[] inputByte = Base64.decodeBase64(str.getBytes(StandardCharsets.UTF_8));

            // base64编码的私钥
            byte[] decoded = Base64.decodeBase64(PRIV_KEY);
            RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));

            // RSA解密
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.DECRYPT_MODE, priKey);
            outStr = new String(cipher.doFinal(inputByte));
        } catch (Exception e) {
            e.printStackTrace();
        }

        return outStr;
    }

    public static void main(String[] args) {
        String str = encrypt("123456");
        log.info(str);
        log.info(decrypt(str));
    }
}
